Honda Giken Kogyo Kabushiki Kaisha

Yoshiharu Ave

Takayoshi Nakayama

Yoichi Iwata

Fumio Hosoda

Kazuhito Kakimoto

Norio Tomobe

Hiroaki Iwasaki

Masashi Uchiyama

Kozo Suzuki

Masayuki Habaguchi

Toru Tochizawa

Junichi Koseki

An air-fuel ratio control system for an internal combustion engine comprises upstream and downstream O2 sensors arranged in the exhaust system of the engine at respective locations upstream and downstream of a catalytic converter, for detecting concentration of oxygen in exhaust gases from the engine. An ECU sets a control variable having a value proportional to the difference between an output from the downstream O2 sensor and a first predetermined reference value, and compares between an output from the upstream O2 sensor and a second predetermined reference value, to thereby calculate an air-fuel ratio correction coefficient, based on results of comparison and the set control variable. The air-fuel ratio of an air-fuel mixture supplied to the engine is controlled based on the calculated air-fuel ratio correction coefficient.

Air-fuel ratio control system for internal combustion engines

There is provided an air-fuel ratio control system for controlling the air-fuel ratio of a mixture supplied to an internal combustion engine having an exhaust passage. The system includes upstream and downstream exhaust gas component concentration sensors arranged in the exhaust passage at respective locations upstream and downstream of a catalytic converter, for detecting concentration of a component contained in exhaust gases. Feedback control of the air-fuel ratio of the mixture is carried out based on a value of a control parameter set based on an output from the downstream exhaust gas component concentration sensor and an output from the upstream exhaust gas component concentration sensor. An inversion period is detected with which the output from the upstream exhaust gas component concentration sensor is inverted from one side to another side with respect to a predetermined level during the feedback control of the air-fuel ratio. It is determined whether or not one of the output from the downstream exhaust gas component concentration sensor and the value of the control parameter falls within a predetermined range. It is determined whether or not the inversion period is within a predetermined time period. Then, deterioration of the upstream exhaust gas component concentration sensor is determined based on results of these determinations.

An evaporative fuel-purging control system for an internal combustion engine includes a mass flowmeter arranged across a purging passage of the engine for measuring a flow rate of a mixture of evaporative fuel and air being purged. A desired flow rate of the mixture is set according to operating conditions of the engine. The desired flow rate of the mixture is compared with a measured flow rate of the mixture obtained by the mass flowmeter, and the opening of a purge control valve arranged across the purging passage is controlled based on results of the comparison.

Evaporative fuel-purging control system for internal combustion engines

A method of controlling the air/fuel ratio for an internal combustion engine set a base value of air/fuel ratio control in accordance with detected engine parameters, and the base value is corrected by a base correction value in order to compensate for the error of the base value. The speed of change in the correction value in the learning control operation is increased when the engine speed is low, or for a predetermined time period after a hot starting of the engine.

Method of controlling the air/fuel ratio for an internal combustion

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